Table Of Contents:
This utility helps in the search for MHC-like motifs in collections of peptide sequences obtained from proteomic analyses.
LAIA motifs program will search for sequence motifs characterized by an anchor position defined by the presence of one or several specific amino acids and will determine the frequency of the different amino acids in each position in the sequence to the right (C-terminal) of the anchor.
Amino acids defining the anchor and the motif size are selectable. An additional position in the peptide (relative to the anchor) can be defined as a second anchor in order to search for more restricted sequence patterns.
Results are displayed graphically and stored in a MS Excel file in the form of frequency tables (absolute and normalized values).
Graphics are also embedded in the Excel document for convenience.
The program was coded in Python (Life is short, thanks Guido), and uses wxPython for the GUI. The GUI was build with wxGlade and the installer was prepared with py2exe and Inno-Setup.
This program has been written by Joaquin Abian (LP CSIC/UAB) in collaboration with Laia Muixí (IBB) (Autonomous University of Barcelona, Catalonia, Spain)
Third-party program versions correspond to those used for the installer available here. Lower versions have not been tested, although they may also be fine.
Three frequency tables can be found in the MS Excel document:
To calculate the corrected frequencies, frequencies for vertebrates are used by default. If you want to change it, see How To Set Specific AA Frequencies below.
Laia Motifs analyses peptide sequence sets that are provided in an input text file, one sequence per line, single letter code.
Comments can be inserted by commenting the line with the tag #.
A test sequence file mhc.txt is provided in the test folder.
Laia Motif corrects the observed frequencies of aminoacids with the naturally observed frequencies in vertebrates. This default frequency data is taken from:
http://www.tiem.utk.edu/bioed/webmodules/aminoacid.htm
These frequencies can be modified by editing the frecuencias.txt file:
C:0.110
A:0.074
name:frog
#This is a comment...
You can download the last version of MHC LAIA motifs here.
After downloading the binary installer, you have to e-mail us at to get your free password and unlock the installation program.
1.00 september 2011
These programs are made to be useful. If you use them and don't work entirely as you expect, let us know about features you think are needed, and we will try to include them in future releases.